Carnivorous Plant Newsletter vol. 40 no. 4 December 2011

Chasing Nepenthes on Cape York, Queensland
Gary W. Wilson • Australian Tropical Herbarium and School of Marine and Tropical Biology
• James Cook University • Cairns, Queensland • Australia • [email protected]
Fanie Venter • Australian Tropical Herbarium • James Cook University • Cairns, Queensland
• Australia
Robyn F. Wilson • School of Earth & Environmental Science • James Cook University • Cairns,
Queensland • Australia
Darren Crayn • Australian Tropical Herbarium • James Cook University • Cairns, Queensland
• Australia
Keywords: field studies: Nepenthes mirabilis, Nepenthes tenax, Nepenthes rowaniae, Cape York, Australia
Little is known of the distribution, status and systematics of Nepenthes in the Austro-Papuan
region and there is some confusion about the number of species present (Clarke & Kruger 2006).
A project currently being conducted by staff and students of the Australian Tropical Herbarium
and James Cook University in Cairns, Queensland and Monash University, Sunway Campus, Kuala Lumpur, Malaysia, is seeking to redress the situation. The study area extends from northern
Queensland across the lowlands of the Trans-Fly Ecoregion in Papua New Guinea and West Papua,
Indonesia, in the area south of Young’s Line. This line delineates the northern margin of the Australia plate and the area is often contiguous when sea levels are lower, most recently c. 8000 years BP
(see Figure 1).
This is a report on a recent field trip by PhD candidate Gary Wilson and staff Fanie Venter and
Robyn Wilson to Cape York to familiarize themselves with the taxa and habitat of Nepenthes there,
Figure 1: The study area.
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Figure 2: Nepenthes mirabilis and expended female fruit at Sheldon Lagoon (left); Fanie
Venter with Nepenthes mirabilis in wetland habitat (right).
collect herbarium specimens and material for DNA sequence analysis, and choose locations for ecological studies to be conducted in the 2011 Dry Season when temperatures and rainfall are lower and
study sites more easily accessible. The Cape constitutes the Cape York bioregion of 127,175 km2, an
area slightly less than that of England. It is renown for its diverse flora and fauna, some of which is
shared with New Guinea, and is a mecca for Australian and overseas visitors alike. Fieldwork on the
Cape is always a challenge; the single access road is unsealed and often impassable during the Wet
Season, c. mid-November through April. A four-wheel drive vehicle is a necessity, temperatures can
be high, and the presence of estuarine crocodile, Crocodylus porosus, makes caution about swamps
and at river-crossings a must.
We undertook the trip in October and early November 2010, heading north at the end of the Dry
Season when water levels in swamps are lowest and most visitors are heading south to escape the impending Wet. Given the time of the year and a forecast for a heavy Wet Season the strategy adopted was
to head for The Tip and work south. While N. mirabilis occurs in a small area south of Cairns in the Wet
Tropics bioregion, Nepenthes on the Cape are of interest because three species, N. mirabilis, N. tenax,
and N. rowaniae, occur there, often growing in distinct habitats but close proximity, and frequently
hybridizing. In addition, several populations of Nepenthes of uncertain taxonomic status occur (see
Clarke & Kruger 2005, 2006; Beasley 2009) and these warrant further investigation.
Australian state and national herbaria records show N. mirabilis has been collected widely in
a number of habitats across the Cape. However, they also show N. tenax and N. rowaniae have
not often been collected and are restricted to swamps and their margins north of the Jardine
River in the northern most part of the Cape. We encountered the first substantial populations
of N. mirabilis at Cockatoo Creek and nearby Sheldon Lagoon in the deep leached sands of
Heathlands National Park; while we were familiar with the species from near Cairns, there was
a palpable sense of excitement in seeing them in this habitat so far from home. Many plants
were in flower and samples were collected and a photographic record was made (see Figure 2).
From here we skirted northwards and found N. mirabilis in every area of suitable habitat, but the
other species remained elusive until we crossed the Jardine River. We then skirted the southern
margins of the Jardine and Sanamere Swamps that flood an area of >400 km2 on a seasonal basis
and are full of crocodiles.
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Figure 3: Nepenthes tenax.
Figure 4: Nepenthes rowaniae in wetland habitat.
We continued on north to Bamaga and touched base with AQIS (Australian Quarantine Inspection Service) staff, part of a team responsible for the health of flora and fauna in the northern Cape and adjacent Torres Strait, for a briefing on local conditions. Then it was through the
Lockerbie Scrub to the site of the colonial settlement of Somerset, type location of N. rowaniae.
We were not successful in finding this species here, probably due to our unfamiliarity with its
habitat requirements. However, we found huge numbers of the toxic Cane Toad, Bufo marinus,
whose introduction to Australia has caused the diminution of so many native species of fauna; at
one site they were so noisy through the night we thought we had stumbled on a Harley-Davidson
convention. We were also concerned about the numbers and activities of feral pigs, Sus scrofa,
which are ripping up extensive areas of Nepenthes habitat. However, N. mirabilis was common
and we surveyed and sampled populations in open freshwater wetland and closed riverine forest habitats. Morphological, morphometric, ecological, and AFLP (amplified fragment length
polymorphism) DNA data from these populations will later be compared with those from the
Wet Tropics and New Guinea.
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Figure 5: Nepenthes tenax (left) and N. mirabilis (right) in Sanamere Swamp.
We next headed to Sadd Point, in the far northeast of the Cape, to collect Nepenthes there. Previous collections from this location had been identified as N. mirabilis, but local botanist John Beasley
had commented (Beasley 2010) that the morphology in some plants varied from those of typical
N. mirabilis. Beasley observed that leaves of some plants retained finely hairy margins and upper
pitchers with characteristics such as wings with finely serrate margins, otherwise typical of lower
pitchers, through to maturity. We made several collections, including one showing a development
sequence from the form commented on by Beasley through mature upper pitchers with morphology
of typical N. mirabilis. While analysis of DNA sequence data will confirm or otherwise this, at the
moment we are happy to assign all of the material to this species.
Back on the main track and just east of the ferry crossing on the Jardine River we finally encountered both N. tenax and N. rowaniae (see Figures 3 and 4) at the head of Cowal Creek in the Sanamere
Swamp. The habitat here is peat over sand with a mixed vegetation of sedges and low shrubs, and is
cut by numerous channels flowing away to creeks and rivers in the north and west. Huge numbers of
Nepenthes are present and it is an exciting and awe-inspiring sight. Nepenthes mirabilis is most com-
Figure 6: Nepenthes mirabilis at Twin Falls.
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mon in slightly drier areas and N. tenax and N.
rowaniae in wetter areas. While the former often
has a scrambling habit and tends to climb into
higher vegetation, the other two form discrete
clumps and sub-shrubs. In some areas N. tenax
and N. mirabilis co-occurred and in these situations the differences in the two species were quite
apparent (see Figure 5). At this location, plants of
each species would be submerged in water in the
Wet Season and frequently subjected to wildfires
during the Dry Season.
Studying N. tenax and N. rowaniae is challenging due to the difficulty in moving about in
this habitat. In addition, the shade temperatures
were 38 and 39˚C on successive days. The sky
was clear and so bright that reviewing digital
images in the camera was almost impossible.
The situation is further complicated as the species hybridize and we believe that several as yet
undescribed entities also occur there. One of
them, colloquially known as “mini-tenax”, occurs deep in the swamps and is difficult to study,
as crocodiles are common in the waist deep wa- Figure 7: Utricularia chrysantha.
ter of their habitat.
We continued our way south, stopping to photograph N. mirabilis on sandstones on the edge of
the water at Twin Falls (see Figure 6) and to have a much-needed swim (it is one of the few places
Figure 8: Nepenthes sp. juvenile lower pitcher at Steve Irwin Reserve.
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Figure 9: Nepenthes mirabilis (upper pitcher) and Robyn Wilson with Nepenthes mirabilis
in habitat at Tozer Gap.
on Cape York where it is safe to do so). Plants of N. mirabilis grew here in a narrow ecotone between
water’s edge and dry surrounding forest and some pitchers were held emergent from stems growing
in the water. A few kilometers further south and a little further upstream at Fruit-bat Falls, in addition to N. mirabilis we photographed the carnivorous Sun Bladderwort, Utricularia chrysantha (see
Figure 7) and the small, but exquisite, Straggly Rush Orchid, Conostalix paludicola (=Dendrobium
lobbii).
North of Weipa, the largest town on Cape York and service centre for a local large alumina mine,
we visited the Steve Irwin Research Reserve on the Wenlock River to study and sample Nepenthes
growing in a spring at the base of a low bauxite plateau. Both N. mirabilis and what had been
identified as N. tenax had previously been collected from the site and we were keen to ascertain the
veracity of the latter, as by this time our experience further north suggested it was unlikely N. tenax
would be present. The substrate at the spring was peaty sand and alluvium and supported a floristically distinct rain forest community that was in excellent condition due to the control of feral pigs
by the resident ranger staff. We recollected both taxa and are of the opinion we are seeing variation
in N. mirabilis – the second taxon (see Figure 8) has some differences in the developmental sequence of lower pitchers and additional study and the results of sequence data analysis will provide
a definitive answer – certainly it is not N. tenax
sensu stricto.
We worked our way south and our final
destination was Tozer Gap in the Iron Range
National Park on the east coast of the Cape.
Here N. mirabilis grows on leached sand in an
elevated heathland (see Figure 9). Iron Range is
a mecca for both botanists and ornithologists,
with a suite of species otherwise only found in
New Guinea present here in the largest area of
lowland rain forest in Australia, so we stopped
work for a day and took in the sights. Several
Figure 10: Myrmecodia beccarii at Tozer Gap. species of epiphytic ant plants (Myrmecodia
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and Hydnophytum) were present and, although not carnivorous, were of interest because colonies of
ants and sometimes the larvae of Theclinesthes butterflies live in them. These ant plants are in the
Rubiaceae and we were delighted to find several plants of Myrmecodia beccarii in flower and fruit
(see Figure 10), the small aromatic white flowers and red-coloured fleshy berries being remarkably
similar to those of Coffea (coffee), also in the Rubiaceae.
Back in Cairns and with the specimens in the drier, tissue samples collected to silica gel archived
for later analysis, and images and morphometrics datasets backed up on the hard drive, we had time
to consider what we had accomplished. In three weeks we had travelled 3000 kilometers, dodged
the descending Wet, surveyed and sampled populations of three species across a range of habitats,
re-sampled a population of dubious taxonomic status, and substantially expanded our knowledge of
the ecology of Nepenthes in Cape York.
Our initial impressions are that N. mirabilis is morphologically variable and occupies a broader
ecological niche and occupies a much wider area than the other two named taxa; that accessing additional populations and conducting ecological studies of N. rowaniae and N. tenax is going to be
challenging, and that more work is required to determine the status of the undetermined taxa. Only
after this work is completed will we extend our activities to similar habitats across Torres Strait on
the island of New Guinea.
Acknowledgements: Collections on this trip were made under Department of Environment and Resource Management (DERM) Permit # WISP05396710. We thank AQIS staff Eric Cottis and James
Bond in Bamaga, Senior Rangers at Heathlands NP, Iron Range NP, and Lakefield NP, Bernard
Charlie of the Injinoo Council, Barry and Shelley Lyon at the Steve Irwin Scientific Reserve, and
John Beasley of Kuranda for their guidance and assistance in our activities.
References
Beasley, J. 2009. Plants of Cape York: the compact guide. Kuranda, Qld., Australia, John Beasley.
Clarke, C.M., and Kruger, R. 2005. Nepenthes rowanae (Nepenthaceae), a remarkable species from
Cape York, Australia. Carniv. Pl. Newsl. 34(2): 36-41.
Clarke, C.M., and Kruger, R. 2006. Nepenthes tenax C.Clarke & R.Kruger (Nepenthaceae), a new
species from Cape York Peninsula, Queensland. Austrobaileya 7(2): 319-324.
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